View Full Version : engine problem /PCM 302

01-27-2003, 05:06 PM
1. engine problem/PCM 302

Thought I woould give the board a try on this one. I have been working on my 82 WAC trying to get it ready for summer. I noticed a little bit of moisture that smelled like gas, so I ran that tank dry.
During the week I put a new wires, coil, plugs, rotor, and cap on. Ran it the next weekend, and after it warmed up it would not idle properly, then it wouldn't run right after a while. So I went through everything, now have the original stuff on. Refilled the port tank and tried again, no luck. Went home and checked the grounds and connections on the engine and ignition areas, still after warmup, problems. then I noticed when the trim tabs are used it makes a connection somewhere and the boat idles and accelerates properly. Any suggestions? Should I call Shamrock? lololol

Date: 09:40 on 03-20-2002

premium member in standard member. 2. Re:engine problem/PCM 302

What you wrote here is a little confusing. Lets see what we can do for you.
"I noticed a little bit of moisture that smelled like gas, so I ran that tank dry."

>>>> Where did you notice this gas/moisture?

"Ran it the next weekend, and after it warmed up it would not idle properly, then it wouldn't run right after a while."

>>>> Sounds like it could be a mis-adjusted choke. Also could be a drip on the secondary side slightly richening the mixture, causing an uneven idle. This would call for a new needle and seat on the secondary side at least, plus a resetting of the float height.

"then I noticed when the trim tabs are used it makes a connection somewhere and the boat idles and accelerates properly."

>>>> This one seems to indicate some kind of electrical issue (Obviously), but exactly what or where, I have no idea. It really calls for you to start troubleshooting the the system with a your trusty DVOM. I would start by checking the primary voltage coming to the distributor. If you have a ballast resistor, one side should show battery voltage and the other something lower, typically around 9V. This is necessary so the points do not recieve too much voltage and erode prematurely. If you have an electronic ignition, then there should be 12V coming to the module. Also go thru the entire boat and check the integrity of all grounds/connections and most of all look hard for any green mold creeping up a wire from the terminal. Shamrock didn't bother to tin most of the connections on your boat, just used crimping pliers. These ain't Cabos, ya know. I would look at the coil, the engine grounds, and the back of the ignition switch, which is often the problem and usually overloked. Also, though its a major PITA, look hard at that ignition solenoid bolted to the back of the motor under the ballast solenoid including the condition of all the wires and terminals screwed to it.

Start with all that happy horse-poop and post back.

"Should I call Shamrock?"

>>>> That would be a GREAT idea. Let us know how their full-time 24/7 mechanical help line works out for you.

rgds, Leprechaun

Here fishie, fishie. . . Come to papa.
Date: 11:10 on 03-20-2002

3. Re:engine problem/PCM 302

My guess is a ground problem. On my 351 the - battery cable goes the the front of the block. Remove these bolts and run a 3/8 16 tap in the holes, rinse with WD40 and put new stainless bolts in. Clean up the lug or replace the cable. I would go through every connector on the boat and clean up or if you have enough wire crimp and solder new lugs on. You can test if this is your problem with jumper cables, hook the cable between the block and battery - . Good luck, these electrical problems are a pain. Clean up your altinator connections too.
Date: 11:11 on 03-20-2002

4. Re:engine problem/PCM 302

OK, 1) everything worked fine
2) While working in the bilge, I stuck my finger in the front drain hole of the SB tank compartment, smelled gas, stuck my finger in the back hole and it was just water. The tank looks like someone was going to fix it then sprayed some can foam on it and called it a day. After replacing the igntion components back to the ones that were in there and no luck, I thought I might have sucked something up from running the SB tank dry.
3) Checked most of what you guys suggested (ground wires) and I will again. What exactly should I look for in the Ignition Switch, proper ground? The problem is, after it cools down or you start it for the first time that day it purrs like a kitten. IT has an electric choke and I unplugged the wires, no luck. I have the pointless distributor upgrade and I did redoe the connection on the terminal of the resistor. I guess when it is doing this I can check voltage to the coil and trace it back? Apparently something is heating up and when I hit the trim tabs I get the voltage I need thru that circuit? Push the throttle wide open and it barely gets on plane, but if you hit the tabs up or down you hear the four barrels and the thing hauls ass. What the hell? It started after the tune-up upgrade coil, wires, plugs etc., but since I am back to what was in it I would have to think it could be anything. Park it and go back the next day, runs like a champ for about 45 minutes. Ignition ground problem after warmup, sounds right?

Date: 13:43 on 03-20-2002

premium member in standard member. 5. Re:engine problem/PCM 302

O.K. - right off, you will need to pull the deckplate off that Strbd tank and have a look at just exactly why you are getting some fuel out the limber holes.
But as far as the engine problem. When you say you redid the connections on the resistor - did you just rewire ACROSS the resistor (like the old points-type distributor would use) or did you pick up your distributor power from the SAME side/same terminal as the ballast resistor's feed wire - which is normally the correct way to wire an electronic distributor? Its got to have 12V to the distributor to work properly.

Here fishie, fishie. . .
Date: 14:02 on 03-20-2002

6. Re:engine problem/PCM 302

I had a similar probelem in my 70 monte when I bought it. It would run great as long as I had the heater motor running. As soon as I turned the heater motor off, it would run like crap.
Then one day it dawned on me, this thing still had points in the distributor. When the previous owner had put the motor in, he just ran a hot wire to the distributor with a full 12 volts. It was cooking the points, and by running the blower motor I was pulling enough current elsewhere that it would run fine.

What I'm trying to say is that your running the trim tab motor is actually pulling current away from something, so the ignition is happy. Once the tab motor isn't drawing any more, there is too much voltage going somewhere.

Did this problem first show up after the new parts were first installed? When you went back to the old parts (presumably with the points) did you put the ballast resistor back into the circuit or still run a full 12 volts to them.

I fully agree with Lep, this is an ignition related problem without a doubt.

Date: 14:19 on 03-20-2002

7. Re:engine problem/PCM 302

Thanks for the reponse. The thing ran fine, the breakerless ignition was already on the boat. I did go in there and wipe it out and smear a little grease around and oil the pad under the rotor. Would one of the springs breaking in there cause this after warmup? Guess I will check the voltage to the coil when it is running bad. On my old boat I installed the breakerless ignition and it looks like that one (bypass the resistor). I haven't pulled the SB tank yet, but I do have the top off and I'll check those connections again. Mostly I lurk on this site so I have read most of what has been posted. Yawl sure are a group of good guys.
The lurker

Date: 14:44 on 03-20-2002

8. Re:engine problem/PCM 302

Checked the grounds again. The voltage at the postive end of the coil is 13.1 and the negative 8.5, when I hit the tabs the voltage was 12.0 pos and 9.5 neg. Could the alternator be causing this, It had 15 volts coming off of it. The alternator only has one wire, is this right, seems like my other boat with a pcm had a harness. Maybe Chuckash is on to something with too much voltage? Could this be a voltage regulator problem, ignition switch, starter solenoid? I'm certainly confused.

Date: 12:20 on 03-22-2002

premium member in standard member. 9. Re:engine problem/PCM 302

I don't know now. You seem to have few issues that might or might not be related.
All the marine alternators I've seen are regulated to 13.9-14.2V - that's because certain of the types of batteries used in boats, namely Gelcells and AGMS are quite sensitive to high-voltage charging and will tolerate recharging (And running) at NO MORE than 14.2V.

I think you have an over-voltage condition going on there. Did you take that votage reading just from the dash gauge or with your DVOM at the alt + terminal?

I really never heard of an alternator running in an over-voltage condition causing this type of issue, but I suppose its hypothetically possible if your iginition can't handle the extra Volts. Maybe someone else here has some experience with this.

Do you know how to swap out an internal regular in an alternator such as yours? Its not all that tough, but you have to know how to keep the brushes retracted against their springs while installing the commutator.

One other thing - you report that you found one of the mechanical advance springs broke/rotted out/what ever, if it is not there, that advance weight it is supposed to hold back at idle will now freely swing out at idle. Or stated another way, the ignition will most certainly begin advancing itself during idle and give you full advance much before the engine will require it, possibly causing a nasty ping and/or other "driveability" issues, INCLUDING the possibility of an erratic idle at low rpm.

You need to fix the alternator and replace that advance spring. Then recheck the alternator's voltage output and re-time the engine. Then go looking for your problem further, it it still exists.

Fix one problem at a time and eventually you'll . . .

get sick of the friggin' boat and sell it to get a bigger one.

Bigger boat, bigger problems.

Just ask Flieman.

Whose 34 Hatt has me salivating.


rgds, Leprechaun

Here fishie, fishie. . .
Date: 19:53 on 03-22-2002

10. Re:engine problem/PCM 302

Well I really do like riding in the boat rather than working on it, try telling my wife that. I was thinking the same thing this weekend, My battery is now at 13.35 volts, reading it with my digital meter and disconnected from everything. So I got desperate and put the resistor back in the ignition circuit, it cut the voltage to the coil down and it ran fine all day. How long before my battery blows up? Oh well guess I am pulling the alternator, I'll post back when I do never rebuilt one before, I'm sure I can.